Currently existing optical detection systems for microfluidic devices are large, expensive, and inflexible. In existing microfluidic device instrumentation, the optical detection system is the costliest subsystem. The size, expense, and rigidity of current optical detection systems result largely from such systems employing multiple high quality lasers for fluorescence excitation, along with multiple charge-coupled device (CCD) cameras for detection.
Alignment and focusing of existing optical detection systems also presents problems. Typically, optics are aligned and focused by viewing fluorescent dye flowing through a channel in a microfluidic device. The dye must be allowed to reach the detection region of the microfluidic device before performing the alignment and focusing process. This can take several minutes for some microfluidic devices. In addition, the fluorescent dye is typically flushed out of the channel after focusing, a time-consuming and sometimes difficult process. Finally, the dye can be expensive and unstable, adding to the cost and complexity of the process.
Therefore, it would be desirable to provide an optical detection system as well as alignment and focusing means and methods that overcome the aforementioned and other disadvantages.